Application of a barrier between edible layers
A layer inside a product which is in contact with another layer sometimes contains a component which may migrate and affect the product quality. To a certain degree, this migration can be prevented. The choice of a barrier ingredient and the application method are critical.
This product can be :
- A wafer on which a light aerated cream is applied
- A biscuit on which a jam with a high warer activity is applied
- 2 layers of ice cream with a different flavour and colour
In most cases the component whose migration must be prevented is water. Its ability to migrate is measured by water activity.
The ingredient used to form a barrier can be:
- Fat, generally a saturated fat which is solid at ambient temperature. Chocolate is such a fat, especially if it is partly made of vegetable cocoa equivalent. Other egetable fat combinations can be used
- Protein-based ingredient: zeine, gluten. Proteins or other hydrocolloids have a limited barrier effect against moisture and are rather used as a barrier against fat migration
How does it work?
The coating operation consists in applying the required quantity in an homogeneous way. It is usually a continuous operation in the industry. After coating, the applied ingredient must be stabilised by cooling or drying depending on its nature.
Fat or hydrocolloid preparation
Application by enrobing or spraying
Stabilisation by drying or cooling
The application system may consist in an enrobing machine or better a spaying machine if only a topical application is desired.
Application spray system
How do you measure your success?
Key quality features
The applied barrier coating must meet precise requirements
The choice of the ingredient should not affect the overall taste of the product
The coating must retain its efficiency. It is a challenge as heating in a later step reduces the barrier effect by melting or swelling, thus facilitating the moisture migration
Key quality parameters
The process is driven by critical factors
In case of fat, the fat must be applied fluid and set rapidly
The dosage must be precise in surface, quantity and homogeneity
It depends on the lower and upper layer nature and texture